1. Field of the Invention. s The present invention relates to digital control systems for hydraulic presses.
2. Description of the Prior Art.
Hydraulic presses such as those disclosed in the Gram U.S. Pat. Nos. 4,457,684 and 4,470,787 are commonly used to manufacture parts with sheet molding compound (SMC). Due to the large forces which are developed during the press cycle, a multiple degree of freedom control system is typically used to control the press during molding operations. An analog control system s representative of those used for this purpose is disclosed in the Larson et al. U.S. Pat. No. 3,800,588.
There is, however, a continuing need for improved control systems for use with SMC presses. The control system must be capable of quickly and accurately driving the press through its press cycle. The control system must also be reliable.